Here's why:
* Association with illness: Pastiness often suggests a lack of color and can be linked to illness or poor health.
* Unattractiveness: In many cultures, a healthy, vibrant complexion is considered attractive. Pastiness can therefore be seen as unattractive.
* Lack of vitality: The word "pasty" implies a lack of energy and vitality, further contributing to its negative connotation.
However, it's important to remember that connotations can be subjective and context-dependent. In some cases, "pasty" might be used in a neutral or even humorous way.